Valve



April 19, 1960 R. F. FALBERG VALVE Original Filed Nov. 7, 1956 3 Sheets-Sheet 1 IN V EN TOR. I By fiafiarfcfzfi/ig ATTORM'FY April 19, 1960 R. F. FALBERG 2,933,282

VALVE Original Filed Nov. 7, 1956 3 Sheets-Sheet 2 i7 INVENTOR. Z 17 W BY flaJEnTJUQk y A TTOPNE'Y April 19,1960

R. F. FALBERG 2,933,282 I VALVE Original Filed Nov. 7, 1956 3 Sheets-Sheet 5 INVENTOR. if

ATTORNEY Unitcd States Patent VALVE Robert F. Falherg, Birmingham, Mich, assignor to General Motors Corporation, Detroit, Micln, a corporation of Delaware Original application November 7, 1956, Serial No. 620372. Divided and this application March 3, 1958, Serial No. 718,676

Claims. (Cl. 251-73) This application is a divisional of application Serial No. 620,972, filed in the U.S. Patent Ofiice November 7, 195 6, entitled Free Piston Engine Starter.

This invention relates to starting free piston engines, gasifiers, or compressors. The invention relates more particularly to automatic starting of free piston machines using an automatic sequential starting cycle and to the devices used for controlling the timing and positioning of elements of the starting system.

Free piston machines require relatively complex starting mechanisms compared to the simple starting devices used in piston type internal combustion engines wherein the pistons are mechanically connected to each other and to the output shaft. Certain operations such as moving the pistons to their outer positions, holding them in this position while providing a build up of pr ssure on the pistons, and subsequently releasing the holding means to allow the pressure to move the pistons inward, require accurate timing and positioning devices in order that these steps be performed in proper sequence. Heretofore, electrical solenoids, relays and solenoid operated valves as well as manual controls have been utilized to perform these functions. Electrically reversible motor driven pumps have been used for creating the force necessary to perform steps during the starting procedure. These electrical components generally are expensive, bulky and require considerable space. Furthermore, complex electrical systems require considerable maintenance.

It is therefore an object of this invention to provide a system employing a unidirectional starting pump for positioning the motor and compressor pistons during the starting cycle.

An additional object is to provide a simple mechanically operated device to control the sequential events of the starting cycle of a free piston machine.

These and other objects and advantages of the invention will be readily apparent from the following specification and drawings which illustrate a preferred embodiment of the invention but which are not to be considered as limiting the invention.

The preferred embodiment of the invention comprises a unidirectional air pump that is alternatively connected to create a vacuum in the cushion chambers of the free piston machine and pull the pistons to their outer position, or connected to create a positive pressure in the chambers to push the pistons to their inner position. The alternative actions depend on the position of a control valve that alternatively connects the pump intake or supply to the cushion chambers. This control valve is initially moved between its evacuating and pressurizing positions by the pistons themselves and then by a spring urged piston acting on the valve through a cam device. The control valve is held in its pressurizing position by a latch mechanism until air pressure from air spring piston has returned to its original position. Initial movement of the control valve from its vacuuming position to its pressurizing position is accomplished mechanically by the engine pistons themselves. The latch means that holds the pistons in their outer positions during the starting cycle is also operated and controlled by fluid pressure in the system.

Referring to the drawings:

Figure 1 is a diagrammatic sectional view of a dual free piston machine;

Figure 2 illustrates schematically a portion of the starter control system for the free piston machine of Figure l in one condition of operation; and

Figure 3 illustrates the starter system in another condition of operation.

Figure l of the drawings diagrammatically shows a dual unit free piston machine that could be used as a gasifier for providing a continuous supply of gases under high pressure and temperature to a prime mover such as a gas turbine, although the machine could be adapted for use as a gas compressor or other purposes than as a gasifier for a turbine.

The engine includes a case or housing 1, a portion of which defines two motor cylinders 2 in which are reciprocably mounted opposed motor pistons 3. Each motor cylinder 2 has inlet ports 4 and exhaust ports 5 at opposite ends of the cylinder. These ports are opened and closed by the motor pistons '3 which are rigid with large compressor pistons 6 that are mounted for reciprocation in the compressor cylinders 7 also formed as part of the engine case 1. Each compressor cylinder has an inlet port 8 controlled by a valve 9 urged to its closed position by spring 10, and an exhaust port 11 controlled by a valve 12 urged to its. closed positionv by a spring 13. The opposed movable masses of the pistons 3 and 6 of each unit are kept in proper relationship with each other by a separate synchronizing linkage 14 for each unit, which may be of known type. The individual units are designated by A and B in Fig. 1. It is to be understood that a single unit machine may also be utilized in the invention.

The two units of the engine are operated on a known supercharged two stroke diesel engine principle. Initial movement of the movable masses 3-ti towards each other causes entrapment of supercharged air and further compression of the air in the motor cylinders 2. At the proper time, fuel is injected by suitable means (not shown) into the compressed air between the motor pistons and is ignited by the heat of compression. The increase in pressure created by the burning fuel acts on the opposed faces of the motor pistons 3 and forces the movable masses 3-6 away from each other.

The compressor cylinder 7 is divided by the compressor piston 6 into a compression chamber 16 and a cushion or bounce chamber 17. When the movable masses 3-6 are moved outward, their outward motion is checked by air trapped in the pneumatic cushion chamber 17, which then possesses practically all of the energy developed by the motor cylinder '2 and restores this energy to the movable masses 3-6 during the next inward stroke. The motor cylinder 2 is scavenged by air drawn in through the inlet valves 9 during outward movement of the masses 36, compressed in chamber 16 during the inward stroke of the masses 3-6, and delivered through the discharge valves 12 into the case chamber 18. A connecting passage 19 provides for equalizing the pressure in the two case chambers 18. On the next outward stroke of the masses 3-6 the air under pressure in the case chamber 18 enters the motor cylinder 2 through inlet port 4 and travels through the motor cylinder 2 and out exhaust ports 5 into the exhaust collector 63 and then to some power generating device such as a gas turbine.

The cushion chambers 17 of each unit are connected together by suitable means 68 to balance the pressures in the opposite chambers. The pressure in the chambersgafteristartinglis; controlled by a stabilizer-"S which is of known type, such as those shown in US. Patent No. 2,355,924. The stabilizer which forms no part of this invention operates only after the starting cycle is completed.

The twounits A and B would normally be connected together by conduit 66 through a normally open isolating valve 1 such as that shown in application U.S. S.N. 584,744 to Warren H. Smith, filed May 14, 1956, now Patent No. 2,839,911. This valve would operate to isolate the chambers after starting when a dephaser D, which may be ofknown type such as those described in',U.S. Patent bio-2,473,204, would act to vary the speed on one unit relative to theother until the .pistons of one unit are approximatelyat the inner dead center when the pistons of the other unit are at outer dead center. The isolatingyalve, stabilizer and dephaser are described in the application andpatents referred to and the details are immaterial to this inventiontand, hence, are not described. The starting controltshown in Figs. 2 and 3 is connected to the machine at conduit 26.

Figs. 2 and. 3 show the portion of the control system used to maneuver the opposed masses 3--6 during the starting operation. The controls consist primarily of: (1).a unidirectional air pump; (2) synchronizer linkages 14 and a latch mechanism 20; and (3) a maneuvering control valve generally indicated at 30. Briefly, the starting cycle'is as follows: (1) the movable masses 36 are moved outward by the creation of a vacuum in the cushion chambers 17; (2) a latching mechanism is then moved into the return path of the linkages 14 connected to the masses 3 -6; (3) a positive pressure is then introduced into the cushion chambers 17 to move the masses 3-6 inward until stopped by the latch mechanism; ('4) the pressure in chambers 17 is built up to a predetermined level; -and'(5) the latch mechanism releases the movable masses 3--6, allowing the compressed air in the chamber 17 to force the movable masses-in towards each other.

The synchronizing and latching mechanisms 14 and 20 include a link 21 secured to a shaft 22 having'on either end a latch member 23 which can be rotated into the path of an arm 24 pivotally mounted on a fixed pivot 25. The arm 24 of each unit has its opposite ends connected by linkage to the opposed compressor pistons 6 of that unit. In the-holding position (Fig. 2) of the latch-mechanism, the latch 23 is in the path of thearm 24-so that when 'air pressure is introduced into chambers 17, pressure'actsonthemovable mass 3-6 to move the sameslowly inward-untilthe arm 24 engages the latch23. Pressure in the 'chamber 17 then rises to a predetermined level, whereupon the controls cause movement of piston 27 of the latch mechanism 20 to rapidlyrnove the linkage 21. This'rotates the shaft 22 and latch '23 to the position shown in Fig. 3, thereby releasing the 'movable'masses 3--6 and allowing the air under pressure in the chamber 17 to move the movable masses -3-6. rapidly. inward.

To control the'rnovement of piston '27 which operates the latch 23 and to alternate the connections between a pump 45 and chamber '17, there is'provided a'positioning control valve assembly indicated at 30. This valve assembly consists of a valve body 31 "enclosing a spool valve-member 32 having four lands 32a, 321;,320 and 32d. The valve body '31 is connected to the pump through passages 46 and 47, to the latch control mechanism by passage 60,"t'o the engine cushion chambers by passage 51, and to the atmospherethrough passages 54,62 and vents 52. 'Forrned'on a portion of the valve member 32 extending through the casing 31 is an enlarged bifurcated section 65 having an inclined cam surface 33 and an adjacent flat surface 33a. A cam follower 34 having a cam roller 34ais 'reciprocably mounted in 'a'housing or chamber'38 attached to valve body 31 for cooperation'withthe surfaces 33 and 33a. The pottion 65 of the valve member 32'carried outside the casing 31 has a latch member 35 pivotally connected thereto by a pin 35a. As shown in Fig. 2, this latch 35 is urged to its upper position by a spring 36. The cam follower 34 is normally urged downward as viewed in the figures by a spring 37 contained within the cam follower chamber 38. A valve spring 39 continuously acts between the left hand end of the valve casing 31 and land 32a of the valve member to urge it to its right hand or evacuating position. The left hand end of the valve 32 is connected to a balance arm 41} by a pin 41. As seen in Fig. 1 the opposite ends of the balance arm 40 are disposed in the path of push rods 42 that have heads 43 formed thereon adapted to engage the opposite ends of the balance arm 46. These push rods are normally urged outward by springs 44. The push rods 42 extend into the compression cylinder 7 and are adapted to be engaged and moved by the compressor piston 6 at the close of the outward movement of the pistons duringthe starting cycle, but are not engaged by the pistons during the normal operating stroke of the pistons when trapped air in the chambers 17 limits outward movement of the pistons 6.

The piston maneuvering and controlling fluid pressures are produced by a fluid pump schematically indicated at 45. This pump may be driven by any suitable means such as an electric motor, air motor or other device and has an intake passage 46 and a supply passage 47. The pump passages 46 and 47 are connected into I the control valve body 31. A passage 51 extends from the valve body 31 to a passage 26 through a chamber 48 in which a check valve 49 is urged by a spring 50 to close the conduit 51 from communication with the passage 26. Passage 26 is connected to the cushion chamhere 17 of the free piston engine. When energized, the

pump 45 acts either to create'a vacuum in the cushion chamber 17 or to create a pressure in that chamber,

depending on the position of the control valve 32. The valve 32 in Fig. 2 is shown connecting the pumpfor pressurizingthe chamber i'i' and in Fig; 3 for evacuating the chamber17.

In the vacuumizing or normal position of Fig. 3' the cam follower 34 is in the upper portion of itsstroke and the roller 34a is in contact with surface 33a, with the spring 39 maintaining the valve 32 in its right hand position. Upon operation of the pump 45 air is withdrawn from chambers 17 through the passage 26, checkvalve 49, passage 51, between lands 32a and 32b of the valve member 32, through intake passage 46, 'and'into "the pump 45. The air is then forced out line47 through the valve body 31 and to the atmosphere throughwents 52. This evacuating of chamber 17 causes the movable masses 3-6 to move towards its outwardmost position until the compressor pistons 6 engage push rods 42 (see Fig. 1). Further movement of the compressor pistons 6 causes enough movement of the push rods 42 and, consequently, balance arm 40 to move the valve "32 slightly to the left as viewed in the figures. This movement of the valve 32 is sufiicient to allow the push rod roller 34a to be moved from a position of rest on surface 33:: to a position 'on the cam surface 33. The force of the cam follower spring 37 imparted to the push rod roller 34!; forces the spool valve 32 to move rapidly to the left by imparting a resultant force tothe'left on the cam 33. During its movement down cam 33, the push rod roller 34a depresses the latch 35 which rotates about its pin 35a. When the cam roller 34a reaches'the bottom of the cam 33, the latch spring 36 returns'the latch to' its normal position as shown in Fig. 2.

Movement of the control valve 32 to the left has connected the pump 45 so that it forces air under pressure into chamber 53 of the latch releasing mechanism and, subsequently, into chamber 17. This action occurs as follows: Referring to Fig. 2 which shows the valve at its pressurizing position, air is drawn from passage 54 into the valve body 31, through a bore 55 in the valve member 32, a port 56 between lands 32b and 32c, into pump intake passage 46, through the pump 45 and into passage 47, through the control valve between lands 32a and 32b, and through passage 51. Pressure in passage 51 first acts to close the check valve 49 and at the same time opens a check valve 57 against the spring 58 and passes into line 59, through the valve body 31 between lands 32c and 32d, into the line 60 which leads into chamber 53 of the latch releasing mechanism. The air under pressure in chamber 53 moves piston 27 to the left against spring 64 and through the linkage 28, 29 and 21, rotates the shaft 22 and the latches 23 to the locking position as shown in Fig. 2. Near the end of its movement to the left the piston 27 pushes the check valve 49 off its seat, allowing air under pressure in line 51 to pass to line 26 and into the chamber 17.

As the air pressure in the cushion chamber 17 gradually builds up, the movable masses 3-6 move slowly to their inner position until the arms 24 of the synchronizing linkages l4 engage the latches 23. Pressure then continues to build up in chamber 17 until the pressure acting through passage 61 on the lower surface of the cam follower piston 34 moves the piston 34 against the spring 37. The valve 32 remains stationary during this upward movement of the cam follower 34 because the cam follower roller 34a follows the contour of the latch 35, which is held against the roller 34a by the spring force of return spring 39. When the cam follower roller 34a reaches the top of the latch 35 the latch 35 is depressed slightly against spring 36 allowing the spring 39 to return the valve 32 to the position shown in Fig. 3, the follower roller 34a returning to its normal position also. The rapid movement of valve 32 to the right (Figure 3) connects the chamber 53 of the latch control mechanism and passage 60 to the atmosphere through valve body 31 between passages 32c and 32d and exhaust passage 62. With the drop in pressure in chamber 53 the spring 64 moves the linkage 28, 29, 21, shaft 22 and latches 23 unlocking the synchronizer linkages and allowing the pressure in chambers 17 to start a rapid inward movement of the masses 36 for the first firing stroke.

After the compresssor piston 6 and motor pistons 3 reach a predetermined inner position fuel is injected into the cylinder 2 and the engine operates under its own power. After the engine starts the pump 45 ceases opera tion and other controls, not shown, operate to regulate the pressure in cushion chamber 17, and to dephase the two free piston units so that a continuous supply of controlled gases under high pressure and temperature are supplied through the exhaust collector 63 to the gas turbine. These controls as well as the gas turbine have not been shown as they form no part of the invention as any form of free piston machine control could be utilized in a machine using the starting system of the present invention.

The operation of the starting system may be briefly summarized as follows: Initially the latch control mechanism 20 and positioning control valve 30 are positioned as shown in Figure 3. The pump 45 is operated whereby air is withdrawn from cushion chamber 17 through passage 26, check valve 49, line 51, between lands 32a and 32b of valve 32, through passage 46 and the pump into line 47, then through the valve body and out vent ports 52. When the pistons 6 reach the outer part of their stroke they engage push rods 42 causing balance arm 40 to move the valve 32 to a position where the cam follower roller 34a engages inclined cam surface 33 and allowing the force of spring 37, which acts through the cam follower 34, to force the valve 32 to the left against spring 39. Movement of valve 32 to the left causes cam follower 34 to move the latch 35 against the spring 36 and when the valve reaches the end of its stroke, Figure 2, the latch is returned by the spring 36 to its upper position blocking movement of the valve 32 to the right.

With the control valve as shown in Figure 2, pump 45 is now connected to draw air through ports 62 or 54 and passage 46 and will force it under pressure through line 47 into passage 51. Pressure in passage 51 acts to close the check valve 49 and also passes through check valve 57, line 59, through the valve 30, line 60 and into chamber 53 where it acts on piston 27 to move the links 28, 29, and 21 aaginst the force of spring 64 to rotate shaft 22 and latch 23 to a blocking position. When the piston 27 has reached the end of its stroke to the left as viewed in the figure it pushes check valve 49 off its seat allowing pressure in line 51 to pass into line 26 and into the cushion chamber 17. The pressure in chamber 17 then moves the pistons 6 inward until the synchronizer arm 24 con.

tacts the latch 23. The pressure in chamber 17 continues to rise and is transmitted through line 61 to act to move the cam follower 34 upward against the force of spring 37, the cam follower 34a meanwhile following the contour of latch 35. When cam follower 34 reaches the upper portion of its stroke, latch 35 is slightly depressed allowing spring 39 to rapidly move valve 32 to the Fig. 3 position, whereupon pressure in chamber 53 acting to hold the latching mechanism in its locking position escapes through passage 60, between lands 32c and 32d and exhaust passage 62. Spring 64 then moves linkage 28, 29 and 21 to move the latch 23 out of the path of linkage arm 24 and allows air under pressure in chamber 17 to rapidly move the pistons 6 inward toward their first firing stroke. The fuel is then injected into combustion chamber )15 and the movable masses 36 forced outward, their outward stroke being limited by air trapped in chamber 17. The continued operation of the free piston machine is then controlled in any known manner as by the stabilizer, dephaser and other controls.

The invention provides an improved control apparatus suitable for use in many applications in the art of free piston machine control and the principles of the invention may easily be utilized in other arts through the use of ordinary skill.

It will be apparent to those skilled in the art that many modifications of the system and components thereof may be made within the scope of the invention which is not to be considered as limited by the detailed description of the embodiment shown.

I claim:

1. A valve actuating mechanism for moving a valve from a first operative position to a second operative position including a valve, a first biasing means for urging said valve to its first position with a predetermined force, a cam surface formed on the valve, a cam follower adapted to engage the cam surface in positions of the valve intermediate the first and second positions, a second biasing means for urging the cam follower into engagement with the cam surface to urge the valve toward its second position with a force greater than that of the first biasing means, a second surface formed on said valve, said cam follower engaging said second surface when the valve is in its first position but inoperative to urge said valve to said second position and means to move said valve from said first position to a position where the cam follower engages the cam surface.

2. A valve actuating mechanism for moving a valve from a first operative position to a second operative position including a valve, a cam surface formed on the valve, a cam follower adapted to engage the cam surface in positions of the valve intermediate the first and second positions, biasing means for urging the cam follower into engagement with the cam surface to urge the valve toward its second position with a predetermined force, means connected to said valve to move the valve from said first position to a position where the cam follower engages the cam surface and thereby urges the valve toward its second position, additional means biasing said valve to said first position with a force less than said predetermined force, means for overcoming said first mentioned biasing means to move saidcam follower away from the valvefand a-latch carried by said valve adapted'to engage "said'car'nfollower when the valve is in its second position to hold the valve in the second position until said cam follower is returned to its position out of engagement with the cam surface whereupon said additional biasing means will move the valve from its second position to its first position.

' 3. A valve actuating'mechanism for moving a valve from a first operative position to a second operative position including a valve, a cam surface formed on the "valve, a cam follower adapted to engage the cam surface in positions of the valve intermediate the first and second positions,' biasing means for urging the cam follower from "an original position of engagement with the valve into engagement With the cam surface to move the valve toward its second positiommeans to move said valve from *said'first position to a position where the cam follower engages the cam surfaces, additional means biasing said valve'to said first position, first mentioned biasing means being'stronger'than the second, fluid pressure means for overcoming said first mentioned biasing means to move "said cam'follower away from the valve, a latch carried by said valve adapted to engage said cam follower when 'between a first and a second position including a valve, a

,member operatively connected to move the valve, said member having two contact surfaces, follower means adapted to successively engage said surfaces upon movement of said member, said follower means engaging said first surface when the valve'is in its first position and engaging the second surface in all positions of the'valve during movement from the first to the second position,

"means biasing said follower into contact with said respective surfaces, said .first surface being'parallel to the axis ofmpvement of said member and the second surface being at an angle to. the axis of movement, means to move the member from afposition where the follower means contacts said first surface to a position where the follower means contacts said second'surfaceto transmit at least a portion of the force of said biasing means to urge the member and valve along its axis to its second position, means to move said follower away from contact with said surfaces, and actuating means connected to said valve for moving it to its first position upon predetermined movement of said follower meansaway from said second surface.

5. A valve operator for moving a valve along an axis between a first and a second position including a valve, a member operatively connected to move the valve, said member having two contact surfaces, follower means adapted to successively engage said surfaces upon movement of said member, said follower means engaging said first surface when the valve is in its first position and engaging the second surface in all positions of the valve during movement from the first to the second position, means biasing said follower into contact with said'respective surfaces, said first surface being parallel to the axis of movement of said member and the second surface being at an angle to the axis of movement, means to move the member from a position where the follower means contacts said first surface to a position where the follower means contacts said second surface to transmit at least a portion of the force of said biasing means to urge the member along its axis and ,valve to its second position, means to move said follower away from contact with said surfaces, actuating means connected to said valve for moving it to its first position upon predetermined movement of said follower means away from said second surface, and holding means carried'by said member adapted to contact said follower means for maintaining said valve in its second position, said predetermined movement of said'follower away from said second surface acting to render said holding means ineffective to maintain the valve in its second positionand thereby allow said actuating means to movesaid-valve to its first position.

References'iiited in thefile of this patent UNITED STATES PATENTS 2,797,061 'Bu'chanan June 25, 1957 2,838,272 Kre'uter June 10, 1958 

